1. Technical Field
The present invention generally relates to a thermal management system, a vehicle embodying such a thermal management system, and methods related thereto. More particularly, the present invention relates to a thermal management system that controls the flow of engine coolant during stoppage of an engine so as to improve the heating performance during engine stop when the interior of the vehicle is heated using an engine coolant. a hybrid electric vehicle having such a system and methods related thereto.
2. Background Art
Internal combustion engines as they are powered by fossil fuels such as gasoline or diesel have many shortcomings such as environmental contamination due to exhaust gas, global warming due to carbon dioxide, respiratory ailments due to increased ozone, etc. Moreover, because the amount of fossil fuels left on earth is limited, they will become exhausted some time in the future
Consequently, various types of electric vehicles have been developed, including but not limited to a pure electric vehicle (EV) driven by operating a drive motor, a hybrid electric vehicle (HEV) driven by an engine and a drive motor, a fuel cell electric vehicle (FCEV) driven by operating a drive motor using electric power generated by a fuel cell.
These electric vehicles are low emission. environmentally-friendly vehicles or zero emission environmentally-friendly vehicles, which can minimize or completely solve the environmental problem and the resource depletion problem. The electric vehicle is equipped with an electric motor for driving the vehicle, a battery (e.g., high-voltage battery) as an energy storage device for supplying electric power to the electric motor, and an inverter for rotating the electric motor. The inverter inverts the phase of electric power supplied from the energy storage device (or fuel cell) based on a control signal applied from a controller to operate the electric motor.
Such an electric vehicle is equipped with converters for power conversion such as a low-voltage DC-DC converter (LDC) for power conversion between a high-voltage battery (i.e., main battery) and a low-voltage battery (i.e., auxiliary battery) and a high-voltage DC-DC converter (HDC) for converting the electric power of the high-voltage battery and supplying the converted power to high-voltage driving circuits.
In addition such an electric vehicle is equipped with a cooling system to extract heat generated from various components such as high-voltage components, thereby cooling such components. such an electric vehicle is equipped with an air conditioning and heating system that are configured an operated to improve the pleasantness of the interior of the vehicle, like what is done for the vehicles with internal combustion engines.
More particularly, the various power electronic components such as motors (e.g., drive motor, radiator fan motor, etc.), DC-DC converters, inverters, high-voltage batteries, etc. for such an electric vehicle are equipped with a water-cooling system including a pipe through which a coolant is supplied and circulated to absorb heat generated from the corresponding component.
Referring now to FIG. 1, there is shown a schematic diagram of a configuration of a typical thermal management system for a hybrid electric vehicle. Such a thermal management system includes an engine cooling system, a heating system that uses engine coolant, and a transmission oil cooling-heating system.
Such a hybrid electric vehicle includes an internal combustion engine, i.e., an engine 10 as a drive source and an engine cooling system that cools the engine 10 by supplying and circulating coolant. Such a hybrid vehicle also includes a heating system that heats the interior of the vehicle using the coolant of the engine 10, and a transmission oil cooling-heating system that cools or heats the oil of a gear box 61 having a transmission also using the coolant of the engine 10.
Such a cooling system includes a heater core 20, through which the coolant flows, which heater core is configured an arranged to extract or absorb heat energy from the coolant. The heat energy extracted or absorbed by the heater core 20 is exchanged or transferred to the air to be supplied to the vehicle interior. Typically, a fan or the like is fluidly coupled to the heater core 20 and the vehicle interior so that the heated air is circulated in the interior of the vehicle. In this way, heat is supplied to the interior of the vehicle.
In addition to including the engine 10 as a driving source and a heat source (e.g., water jacket of the engine block) and the heater core 20, such a hybrid electric vehicle also includes a radiator 30, a heat exchanger 40, gear box 61 and electric motor 62 (e.g., a drive motor). The radiator is provided to radiate the heat of the engine 10 through the heat exchange between the coolant passing through the engine 10 and the outside air. The heat exchanger 40 exchanges heat between the working oil of the gear box 61 and the coolant and is performed to heat or cool the gear box 61 (such as a transmission) connected to an electric motor 62 (e.g., drive motor).
Such a hybrid vehicle also includes a coolant line 51 that is connected between the engine 10, the heater core 20, the heat exchanger 40, and the radiator 30 such that the coolant is circulated there through. Also included is a coolant pump 50 that circulates the coolant through the coolant line 51, a thermostat 52 that controls the flow of the coolant so as to selectively pass through the radiator 30, and an oil line 41 that is connected between the heat exchanger 40 and the gear box 61 for oil circulation.
In this configuration of the thermal management system, when the engine 10 is being operated (e.g., vehicle being driven) the coolant absorbs the heat of the engine 10 and this heat is heat-exchanged with the air to be supplied to the interior of the vehicle in the heater core 20, thereby heating the interior of the vehicle.
When the engine 10 is stopped, the coolant absorbs heat from the oil which cools the gear box 61 in the heat exchanger 40 and is heat-exchanged with the air in the heater core 20, thereby supplying heat required to heat the interior of the vehicle.
When it is necessary to rapidly increase the temperature of the engine 10 so as to reduce exhaust gas and improve fuel efficiency after turning off the engine 10, it is possible to heat the engine using the heat from the oil of the heat exchanger 40 and absorbed by the coolant.
Restart
In the above-described system, however, if the engine is stopped and if the interior of the vehicle is heated using the latent heat of the engine 10 or using the heat transferred from the heat exchanger 40 to the coolant or if the temperature of the engine 10 is below the critical point, it is inevitably necessary to start the engine 10 for the heating of the interior of the vehicle.
While the coolant absorbs heat from the oil of the heat exchanger 40 and the interior of the vehicle is heated in a state, when the engine 10 is turned off the coolant passes through the engine at all times. This allows heat to be removed from the coolant by the cold engine 10, and as a result the heat for heating the interior of the vehicle is insufficient.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.
It thus would be desirable to provide a new thermal management system, particularly for a hybrid electric vehicle, and methods related thereto. It would be particularly desirable to provide such a system and method that would improve the heating performance of the interior of a vehicle when it being heated using engine coolant and the engine is off as compared to prior art systems. Such thermal management systems preferably would be no more complicated than prior art systems and such methods would not increase the skill required for operators of such vehicles.